The aim of this project is to isolate and characterize mutants of the malaria parasite Plasmodium falciparum that can be used to 1) analyze the pathogenicity of the parasite and 2) construct a defective non-pathogenic strain that can cause a premunition of residual type of immunity. In vitro cultivation of P. falciparum and mutagenesis using chemical mutagens will be carried out. A variety of strategies for isolating conditional lethal and drug sensitive mutants will be explored. Parasite mutants affecting RBC-endothelial cell adhesion and merozoite invasion will be isolated and analyzed.